Cryo balloon

ABSTRACT

Devices and methods for performing cryo therapy, cryo ablation or cryoplasty. A cryo therapy apparatus may comprise an elongate shaft, a cooling member disposed at the distal end of the shaft, and a pressure gauge coupled to the cooling member.

FIELD OF THE INVENTION

The present invention pertains generally to the field of cryo therapy.More particularly, the present invention pertains to cryo ablationcatheters for use in causing cold-induced necrosis and cryoplastycatheters for use in causing apoptosis to prevent restenosis.

DESCRIPTION OF THE RELATED ART

A number of medical conditions may be treated using ablative techniquesor devices. Ablative techniques, generally, result in destroying thefunction of abnormal tissue at an area of interest. Destroying thefunction of the abnormal tissue may result in an efficacious treatmentfor a medical condition. For example, atrial fibrillation may be theresult of abnormal electrical activity in the left atrium and thepulmonary vein, and may be treatable by ablation of the abnormal tissuewithin the left atrium and/or the pulmonary vein.

Atrial fibrillation is a serious medical condition that is the result ofabnormal electrical activity within the heart. This abnormal activitymay occur at regions of the heart including the sino-atrial (SA) node,the atriovenricular (AV) node, the bundle of His, or within other areasof cardiac tissue. Moreover, atrial fibrillation may be caused byabnormal activity within a isolated focal center within the heart. It isbelieved that these foci can originate within the pulmonary vein,particularly the superior pulmonary veins.

Minimally invasive techniques have been described that use ablationcatheters to target the pulmonary vein with the hope of ablating focihaving abnormal electrical activity. The techniques typically arecharacterized by application of energy to cause lesions within the focior other areas possessing abnormal electrical activity.

Some ablation devices utilize radio frequency (RF) energy for ablation.The RF energy devices may be used to ablate an area of interest withheat. The use of RF energy for ablation may, however, lead to untowardhealing responses such as collagen build up at the area of interestafter treatment. Moreover, RF ablation of within an atrium may decreaseatrial output. A need, therefore, exists for ablative devices andmethods that include improved healing responses.

An alternative treatment strategy has been developed that uses coolingenergy for ablation. This method, termed cryoplasty or cryo therapy, maybe used to cool the lesion to freeze a portion of the affected area. Forexample, cryoplasty may be used to freeze a lesion within a blood vesselto induce apoptosis or remodeling that might otherwise lead torestenosis or recoil. In addition to its potential utility in preventingand slowing restenosis and addressing recoil, cryo therapy may be usedfor ablation techniques. For example, cryo therapy may be efficacious invaricose vein treatment of incompetent valves, valvular disease, mitralvalve regurgitation therapy, atrial fibrillation, gastric refluxdisease, gastro esophageal reflux disease, GURD, esophageal disease,cancer treatment including stomach or uterine cancer, etc.

SUMMARY OF THE INVENTION

The present invention pertains to cryo therapy catheters. Moreparticularly, the present invention comprises a cryo therapy deviceincluding a pressure gauge to monitor the pressure within an inflatableportion of the cryo therapy apparatus and a pressure release tube thatmay comprise a conduit for coolant to escape should pressure become toogreat. The present invention can be used to ablate tissue (such asabnormal tissue within the pulmonary vein), ablate tissue in orderprevent restenosis in the vasculature and cardiac tissue, and ablateother target regions where cryo therapy may have beneficial effects.

The cryo therapy device may include an elongate shaft having a coolingmember disposed at the distal end thereof. The pressure gauge may becoupled to the cooling member. The pressure gauge may comprise a straingauge that may include a direct or indirect measure of pressure withinthe inner member that may be quantified directly or indirectly by aclinician. In an alternate embodiment, the pressure gauge may comprise ahorizontal strain gauge. A horizontal strain gauge is substantiallysimilar to the strain gauge detailed above except that it may bedisposed at the inner member in a differing pattern. The pressure gaugemay also be an optical, piezoelectric, magnetic, or mechanical microsensors disposed within the cryo chamber.

The pressure release tube has a proximal end, a distal end, and a lumenextending therethrough. A removable valve may be disposed at theproximal end of the pressure release tube. The removable valve may beremoved from the pressure release tube to allow pressure to escape fromthe inner member. In addition, a pressure-sensitive valve may bedisposed at the distal end of the pressure release tube. Thepressure-sensitive valve is understood to be a valve disposed at thedistal end that will provide an opening to the lumen of the pressurerelease tube if the pressure within the inner member becomes too great.The pressure relief valve may also be a pressure relief mechanism suchas a puncture device such as an RF relief cutter, or alternatively amechanical needle to puncture the balloon and create a controlledrelease of gas. The controlled release of gas may be into an isolationchamber surrounding the cryo chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-section of a cryo therapy device having a pressuregauge and a pressure release tube;

FIG. 2 is a partial cross-section of a cryo therapy device having a fuselink coupled to the pressure relief tube;

FIG. 3 is a partial cross-section of a cryo therapy device having arelief cutter coupled to the inner surface of the inner member of thecooling chamber; and

FIG. 4 is a cross-section of a cryo therapy device having an alternatepressure gauge and a pressure release tube.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description should be read with reference to the drawingswherein like reference numerals indicate like elements throughout theseveral views. The detailed description and drawings represent selectembodiments and are not intended to be limiting.

FIG. 1 is a cross-section of a cryo therapy device 10 having a pressuregauge 12 and a pressure release tube 14. Pressure gauge 12 is coupled toa cooling member 16, for example on an inner member 26. Pressure gauge12 may be used to quantify pressure within cooling member 16. Coolingmember 16 is coupled to an elongate shaft 18. In addition, at least aportion of pressure relief tube 14 is disposed within cooling member 16.Pressure relief tube 14 may be used to release inflation/cooling mediafrom cooling member 16. This could be done, for example, when thepressure in cooling member 16 as detected by gauge 12 is in excess of adesired limit.

Cryo therapy device 10 may use heat transfer to perform a number ofprocedures including pulmonary vein ablation, pulmonary artery ablation,atrial fibrillation, arrhythmia, and other conditions. Moreover, cryotherapy device 10 may be used to prevent restenosis in the vasculature(including the pulmonary artery and vein), cardiac tissue (includingatria and ventricles), and other target regions where cryoplasty mayhave beneficial effects.

Shaft 18 includes a proximal end 20 and a distal end 22. Shaft 18 may begenerally tubular and may be comprised of material including, but notlimited to, metals, stainless steel, nickel alloys, nickel-titaniumalloys, thermoplastics, high performance engineering resins, fluorinatedethylene propylene (FEP), polymer, polyethylene (PE), polypropylene(PP), polyvinylchloride (PVC), polyurethane, polytetrafluoroethylene(PTFE), polyether block amide (PEBA), polyether-ether ketone (PEEK),polyimide, polyamide, polyphenylene sulfide (PPS), polyphenylene oxide(PPO), polysufone, nylon, perfluoro(propyl vinyl ether) (PFA), andcombinations thereof. In addition, a guidewire tube 19 having aguidewire lumen 21 extending therethrough (and through cooling member16) may be disposed within shaft 18.

Cooling member 16 may be disposed at a distal end 22 of shaft 18.Cooling member 16 may comprise an outer member 24, inner member 26, andan annular space 28 therebetween. As an alternate feature, a vacuumsource can be fluidly connected to device 10 to evacuate space 28. Bothouter member 24 and inner member 26 can be, for example, balloonscomprised of polyether block amide (PEBA). Outer member 24 and innermember 26 can have a burst pressure, for example, of about 6 to 24atmospheres. Polyether block amide is commercially available fromAtochem Polymers of Birdsboro, Pa., under the trade name PEBAX.Alternatively, cooling member 16 may be comprised of materials listedabove.

Inner member 26 is in fluid communication with a coolant source. Forexample, the coolant source may be coupled to inner member 26 by aninflation tube 30 and a drain tube 32 each disposed within shaft 18. Theinflation tube and the drain tube are substantially similar to analogousobjects disclosed within U.S. Pat. No. 5,868,735 to Lafontaine and U.S.patent application Ser. No. 09/849,892 to Lafontaine, the entiredisclosures of which are hereby incorporated by reference. Outer member24 may contain coolant which may escape from inner member 26. Cryotherapy device 10 may further comprise additional elements and featuresdisclosed within the above-incorporated references.

Proximal end 20 of elongate shaft 18 may be connected to a manifold 34.Manifold 34 may comprise a coolant source. For example, manifold 34 maycomprise a coolant source coupled to inner member 26 via inflation tube30. Additionally, manifold 34 may comprise means for actuating (i.e.,inflating) inner member 26 adapted to connect to an inflation pump.

Inner member 26 may further comprise an inner surface 36 and an outersurface 38. Pressure gauge 12 may be disposed at outer surface 38. In analternative embodiment, pressure gauge 12 may be disposed at innersurface 36. Pressure gauge 12 may be connectable to manifold 34 by aconnector 40.

Pressure gauge 12 may comprise, for example, a strain gauge, fuse link,optical transmitter with a fiber optic output, etc. In general, thelength of pressure gauge 12 may be altered by increasing the size and/orpressure of inner member 26 (e.g., by inflation with a coolant).Therefore, the strain of pressure gauge 12 may comprise a direct orindirect measure of pressure within inner member 26. The fuse linkembodiment would measure pressure in a threshold manner. For example,when the balloon pressure expands the balloon to a size that breaks thelink, the interruption of conductivity would be sensed and indicateexcessive pressure. The optical transmitter with a fiber optic outputembodiment would allow a user to visualize inner member 26 to determineif pressure should be altered. For example, connector 40 may comprise afiber optic output and manifold 34 may include a optical transmitter. Ingeneral, optical visualization may be accomplished in any manner that isknown in the art.

Means for quantifying strain and/or stress may include an analog readingor display, a digital reading or display, a connector for coupling to acomputerized system for quantifying strain, a computerized system forprocessing other data, and combinations thereof. A person of ordinaryskill in the art would be familiar with these and alternative means forquantifying strain according to multiple embodiments of the inventionand converting the strain measurement to a pressure measurement.

Pressure release tube 14 may comprise a proximal end 42, a distal end44, and a lumen 46 extending therethrough. Pressure release tube 14 maybe comprised of materials similar to those listed above. Pressurerelease tube 14 may comprise a conduit for a coolant to escape frominner member 26 if pressure therein exceeds a desired limit. Forexample, inner member 26 may comprise a burst pressure of 8 atmospheres.Pressure release tube 14 may be in fluid communication with inner member26. If the pressure within inner member 26 approaches the burstpressure, coolant may be removed from inner member 26 through pressurerelease tube 14.

A removable valve 48 may be disposed at proximal end 42 of pressurerelease tube 14. According to this embodiment, if pressure within innermember 26 approaches a desired limit, for example, the burst pressure,removable valve 48 may be removed from pressure release tube 14 to allowpressure to escape inner member 26. Removable valve 48 may be locatedproximate manifold 34 so that it may be available to a user of cryotherapy device 10.

In use, pressure within inner member 26 may be measured by pressuregauge 12 and may be quantified. The amount of pressure within innermember 26 may be available to a clinician performing a medicalprocedure. If the pressure becomes too great within inner member 26 orapproaches the burst pressure thereof, the clinician may removeremovable valve 48 from pressure release tube 14. Removing removablevalve 48 from pressure release tube 14 will reduce pressure within innermember 16.

A pressure-sensitive valve 50 may be disposed at distal end 44 ofpressure relief tube 14. Pressure-sensitive valve 50 is understood to bea valve disposed at distal end 44 that will provide an opening to lumen46 if the pressure within inner member 26 becomes too great (e.g.,approaches a desired limit, such as the burst pressure of inner member26). Pressure-sensitive valve 50 may be used with or without removablevalve 48.

FIG. 2 is a partial cross-section of cryo therapy device 10 having afuse link 52 coupled to pressure relief tube 14. Fuse link 52 may beused independently or in conjunction with valve 48, cap 50, or both.Fuse link 52 includes a portion that covers a vent opening 54 withinpressure relief tube 14 and is coupled to pressure sensor (P) such thatwhen pressure exceeds a threshold level, current (I) is increased withinfuse link 52 sufficient to burn fuse link 52 and expose vent opening 54,which allows cooling chamber 16 to be vented. The pressure sensor maycomprise a number of objects such as strain gauge 12, a piezoelectricMEMS (microelectromechanical systems) sensors, a fiber optic sensor,optical sensors, walls of cooling chamber 16, magnetic or mechanicalmicro sensors disposed within cooling chamber 16, etc. It should benoted that FIG. 2 depicts the pressure gauge as being connected toconnector 40 of pressure gauge 12 at manifold 34. However, any of thepressure sensors listed above may be substituted and coupled to fuselink 52 at any convenient location such as at manifold 34, withincooling chamber 16, etc.

The pressure sensor and fuse link 52 may be coupled by an electricalcircuit. For example, the pressure signal may be amplified and thencompared with a pressure threshold at a second amplifier. The pressurethreshold may be set a desired level near and/or less than the burstpressure of inner member 26. Pressure in excess of the burst pressuremay be further amplified (for example, to correct or increase thesignal) an go on burn fuse link 52 and expose opening 54. It can beappreciated that other suitable configurations of electrical circuitsmay be substituted without departing from the spirit of the invention.

FIG. 3 is a partial cross-section of cryo therapy device 10 having arelief cutter 56 coupled to inner surface 36 of inner member 26. Reliefcutter 56 may be used independently or in conjunction with valve 48, cap50, fuse link 52, or combinations thereof. Relief cutter 56 may becomprised of one or more wires 58 (e.g., about 0.007 inches in diameter,more, or less) disposed along inner surface 36 of inner member 26. Forexample, relief cutter 56 may comprise two parallel insulated wiresinstalled on inner surface 36. The wires may be spaced a distance (e.g.,0.02 about inches, more, or less) and be connected to source ofpotential energy (V) such as a radio-frequency (RF) energy source, alaser energy source, an ultrasonic energy source, etc. Electrodes 60 maybe disposed on the ends of wires 58 for generating a spark or othercutting means. In an alternative embodiment, relief cutter 56 maycomprise a mechanical puncture device such as a needle, a pull wire, orother suitable object.

To actuate relief cutter 56, energy (RF) is applied to wires 58, whichcreates a spark or other suitable cutting means at electrodes 60. Thespark can result in a relatively small hole (e.g., about 0.25 inches indiameter, more, or less) within inner member 26. The hole allows coolantcontained within inner member 26 to be vented out into outer member 24and out of the catheter through an outer lumen 62. Outer lumen 62 is influid communication with manifold 34 so that any vented coolant may becontained therein. For example, manifold 34 may includes an opening 64for cooling to be vented through and into a holding vessel withinmanifold 34. It is believed that relief cutter 56 will create smallholes within inner member 26 without causing further tearing ordissection of inner member 26.

Relief cutter 56, may be connected to a pressure gauge (e.g., straingauge 12 and others described above) via an electrical circuit. This mayallow automated actuation of relief cutter 56 in the event of pressureapproaching the burst pressure of inner member 26. For example, theenergy source may be switched on by an amplified signal from thepressure gauge (similar to how the pressure signal actuates fuse link52).

FIG. 4 is a cross-section of cryo therapy device 110 having an alternatepressure gauge 112 and a pressure relief tube 14. Cryo therapy device110 is substantially similar to cryo therapy device 10 except thatpressure gauge 112 comprises a horizontal strain gauge or fuse link. Ahorizontal strain gauge is substantially similar to the strain gaugedetailed above except that it may be disposed at inner member 26 in adiffering pattern. The differing pattern may be capable of quantifying adifferent distribution of pressure within inner member 26. It can beappreciated that any number of differing shapes or patterns may be usedfor pressure gauge 112 without departing from the spirit of theinvention.

Similar to what is disclosed above cryo therapy device 110 may furtherinclude pressure relief tube 14. Further, device 110 may include fuselink 52 and/or relief cutter 56. Fuse link 52 and/or relief cutter 56may be used in conjunction with pressure gauge 112 or with other objectsor configurations described above.

Numerous advantages of the invention covered by this document have beenset forth in the foregoing description. It will be understood, however,that this disclosure is, in many respects, only illustrative. Changesmay be made in details, particularly in matters of shape, size, andarrangement of steps without exceeding the scope of the invention. Theinvention's scope is, of course, defined in the language in which theappended claims are expressed.

1. A cryo therapy device, comprising: an elongate shaft having aproximal end and a distal end; a cooling member disposed at the distalend, wherein the cooling member includes an outer member and an innermember; an inflation tube disposed within the elongate shaft; a draintube disposed within the elongate shaft; a pressure sensor that isdisposed near the distal end of the elongate shaft to provide anindication of the pressure within the inner member; and a manifolddisposed at the proximal end of the elongate shaft, wherein the pressuresensor is coupled to the manifold by a connector.
 2. A cryo therapydevice in accordance with claim 1, wherein the pressure sensor isdirectly coupled to the inner member.
 3. The cryo therapy device inaccordance with claim 1, wherein the pressure sensor comprises a straingauge.
 4. The cryo therapy device in accordance with claim 1, whereinthe inner member further comprises an outer surface and an innersurface.
 5. The cryo therapy device in accordance with claim 4, furthercomprising a relief cutter coupled to the inner surface of the innermember.
 6. The cryo therapy device in accordance with claim 5, whereinthe relief cutter is a radio-frequency energy source.
 7. The cryotherapy device in accordance with claim 5, wherein the relief cutter isa laser energy source connected to a relief valve by fiber optic cable.8. The cryo therapy device in accordance with claim 5, wherein therelief cutter is an ultrasonic energy source mechanically coupled to arelief valve.
 9. A cryo therapy device, comprising: an elongate shafthaving a proximal end and a distal end; a cooling member disposed at thedistal end, wherein the cooling member includes an outer member and aninner member; an inflation tube disposed within the elongate shaft; adrain tube disposed within the elongate shaft; a pressure sensor that isdisposed near the distal end of the elongate shaft to provide anindication of the pressure within the inner member; and a pressurerelease tube having a proximal end, a distal end, and a lumen extendingextending therethrough.
 10. The cryo therapy device in accordance withclaim 9, wherein the pressure release tube is in fluid communicationwith the inner member.
 11. The cryo therapy device in accordance withclaim 10, wherein the pressure release tube further comprises aremovable valve disposed at the proximal end thereof.
 12. The cryotherapy device in accordance with claim 9, wherein the pressure releasetube further comprises a pressure-sensitive valve disposed at the distalend thereof.
 13. The cryo therapy device in accordance with claim 9,further comprising a fuse link coupled to the pressure release tube. 14.The cryo therapy device in accordance with claim 13, wherein the fuselink is disposed over an opening within the pressure relief tube andwherein the fuse link is coupled to the pressure sensor.
 15. The cryotherapy device in accordance with claim 9, wherein the inner memberfurther comprises an outer surface and an inner surface.
 16. The cryotherapy device in accordance with claim 15, further comprising a reliefcutter coupled to the inner surface of the inner member.
 17. cryotherapy device in accordance with claim 16, wherein the relief cutter isa radio-frequency energy source.
 18. The cryo therapy device inaccordance with claim 16, wherein the relief cutter is a laser energysource connected to a relief valve by fiber optic cable.
 19. The cryotherapy device in accordance with claim 16, wherein the relief cutter isan ultrasonic energy source mechanically coupled to a relief valve. 20.A cryo therapy device, comprising: an elongate shaft having a proximalend and a distal end; a manifold disposed at the proximal end; a coolingmember disposed at the distal end; wherein the cooling member includesan inner member and an outer member; a pressure gauge coupled to themanifold by a connector; an inflation tube disposed within the shaft; adrain tube disposed within the shaft; and a pressure release tube influid communication with the inner member.
 21. The cryo therapy devicein accordance with claim 20, wherein the pressure gauge includes astrain gauge.
 22. The cryo therapy device in accordance with claim 20,wherein the pressure gauge includes a fuse link.
 23. The cryo therapydevice in accordance with claim 20, wherein the inner member furthercomprises an outer surface and an inner surface.
 24. The cryo therapydevice in accordance with claim 23, wherein the pressure gauge iscoupled to the inner surface.
 25. The cryo therapy device in accordancewith claim 23, wherein the pressure gauge is coupled to the outersurface.
 26. The cryo therapy device in accordance with claim 20,wherein the pressure release tube includes a proximal end, a distal end,and a lumen extending therethrough.
 27. The cryo therapy device inaccordance with claim 26, wherein the pressure release tube furthercomprises a removable valve disposed at the proximal end thereof. 28.The cryo therapy device in accordance with claim 26, wherein thepressure release tube further comprises a pressure-sensitive valvedisposed at the distal end thereof.
 29. The cryo therapy device inaccordance with claim 26, further comprising a fuse link coupled to thepressure release tube, wherein the fuse link is disposed over an openingwithin the pressure relief tube and wherein the fuse link is coupled tothe pressure gauge.
 30. A method of performing cryoplasty, comprisingthe steps of: providing a cryo therapy device including an elongateshaft having a proximal end and a distal end, a manifold disposed at theproximal end, a cooling member disposed at the distal end, wherein thecooling member includes an outer member and an inner member, and apressure gauge coupled to the inner member and coupled to the manifoldby a connector such that pressure within the inner member may bequantified by the manifold; advancing the cryo therapy device to an areaof interest; inflating the inner member of the cooling member with acoolant to a pressure; quantifying the pressure with the pressure gauge;and cooling the area of interest with the cooling member.
 31. The methodin accordance with claim 30, wherein the pressure gauge comprises astrain gauge and wherein the step of quantifying the pressure with thepressure gauge includes quantifying strain.
 32. The method in accordancewith claim 30, wherein the inner member further comprises an outersurface and an inner surface.
 33. The method in accordance with claim32, wherein the pressure gauge is coupled to the inner surface andwherein the step of quantifying the pressure with the pressure gaugeincludes quantifying pressure at the inner surface.
 34. The method inaccordance with claim 32, wherein the pressure gauge is coupled to theouter surface and wherein the step of quantifying the pressure with thepressure gauge includes quantifying pressure at the outer surface. 35.The method in accordance with claim 30, further comprising a pressurerelease tube having a proximal end, a distal end, and a lumen extendingtherethrough.
 36. The method in accordance with claim 35, wherein thepressure release tube further comprises a removable valve disposed atthe proximal end thereof and further comprising the step of removing theremovable valve from the pressure release tube in order to reducepressure within the inner member.
 37. The method in accordance withclaim 35, wherein the pressure release tube further comprises apressure-sensitive valve disposed at the distal end thereof and furthercomprising the step of reducing pressure within the inner member.